Zapovednik is an established term on the territory of the former Soviet Union for a protected area which is kept "forever wild". It is the highest degree of environmental protection for the assigned areas, which are strictly protected and access to the public is restricted.

A nature reserve is a protected area of importance for flora, fauna, funga, or features of geological or other special interest, which is reserved and managed for purposes of conservation and to provide special opportunities for study or research. They may be designated by government institutions in some countries, or by private landowners, such as charities and research institutions. Nature reserves fall into different IUCN categories depending on the level of protection afforded by local laws. Normally it is more strictly protected than a nature park. Various jurisdictions may use other terminology, such as ecological protection area or private protected area in legislation and in official titles of the reserves.